Day two of the Boston Marathon bombing trial continued on Thursday as bombing victim Jeff Bauman testified about his run-in with one of the accused bombers just moments before the attack in 2013.

On trial is 21-year-old Dzhokhar Tsarnaev, who is facing 30 charges and the death penalty for his role in the planned attack, which killed three people and injured 264 others on April 15, 2013. According to his defense team, Tsarnaev participated in the bombing when he was 19 years old because he was dominated and motivated by his now-deceased older brother, Tamerlan, 26. Tamerlan, however, died three days after the marathon bombing during a shootout with police.

While on the stand, Bauman, who lost his legs in a bomb explosion, said he noticed Tamerlan standing near him at the finish line. Bauman said he was wearing a black cap, aviator sunglasses and a hoodie and was not cheering like the rest of the crowd.

"It looked very suspicious. He was alone. He didn't look like he was enjoying the race," said the double-amputee, according to USA Today.

Bauman said that he also noticed Tamerlan's backpack was left on the ground a few moments later.

"I figured somebody just forgot it," he said.

Boston Police Officer Frank Chiola also testified on Thursday, recalling that he rushed in the direction of the sound and smoke after a second bomb went off 30 yards behind him.

"There were people on the ground," Chiola said describing the scene. "You couldn't tell who was alive or dead. It was chaos."

Chiola added that he performed CPR on a victim named Crystal.

"She was suffering. She was in pain and shock. From the waist down, it's really tough to describe. It was complete mutilation," Chiola said about the woman.

On Wednesday, Rebekah Gregory, who lost much of her left leg, gave an emotional testimony in the federal court about how she could not help her 5-year-old son during the blast because her own injuries were too severe.

"My bones were lying next to me on the sidewalk," Gregory said on the stand. "At that point, I felt that was the day I would die."

Following her testimony, Gregory posted an open letter to Tsarnaev on Facebook admitting that he haunted her dreams since the bombing, but that she no long fears him now that she has faced him in court.

"I looked at you right in the face.... and realized I wasn't afraid anymore," Gregory wrote, reports the New York Times. "And today I realized that sitting across from you was somehow the crazy kind of step forward that I needed all along."

During opening statements on Wednesday, Assistant U.S. Attorney William Weinreb said: "The defendant's goal that day was to maim and kill as many victims as possible," Weinreb said. "He believed that he was a soldier in a holy war against Americans. He believed he had taken a step toward reaching paradise. That was his motive for committing these crimes."

Defense lawyer Judy Clarke, on the other hand, asked the jury to keep an open mind and suggested that Tamerlan was the mastermind behind the attack.

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